Urethane foams with reduced smoke levels

ABSTRACT

THIS INVENTION RELATES TO FIRE RETARDANT POLYURETHANE FOAMS HAVING RECUCED SMOKE LEVELS. THE INVENTION COMPRISES INCORPORATING CHLORENDIC ACID INTO A FIRE-RETARDANT FOAM FORMULATION.

3,647,724 Patented Mar. 7, 1972 United States Patent 06cc A B S TR A CTOF THE DISCLOSURE This invention relates to fire retardant polyurethanefoams having reduced smoke levels. The invention comprises incorporatingchlorendic acid into a fire-retardant foam formulation...

' STATE OF THE ART Increasing attention. has been placed on the amountof smoke generated from fire retardant polyurethane foams. It is evidentthat even a polyurethane foam having a low flame spread may create ahazard if the smoke released when the foam is in contact with'the flameis suflicient to trap occupants in an enclosed space by obscuring theirvision or hampering their ability to breathe. Methods have beendeveloped for measuring this amount of smoke evolved, for example, seeJournal of Cellular Plastics, January, 1967, pages 41-43. Likewise, theUnderwriters Laboratory has developed tests and ratings for measuringsmoke evolution. (For example, UL-E84 tunnel tests, as well as UL 7 23.)

I DESCRIPTION OF THE INVENTION It has now been found that chlorendicacid, when incorporated into the phosphorus-containing polyurethane fireretardant foam formulation greatly reduces the amount of smoke generatedby the foamwithout substantially detracting from the foam properties.This is surprising since most acids as a class are either ineffective inreducing smoke generation or significantly degrade foam properties. Theamount of chlorendic acid employed in the foams of this invention isthat amount which is an effective smoke diminishing amount. Generallyabout percent to about 40 percent by weight of the total composition isemployed. Preferably, about to about 25 percent by weight of the totalcomposition is employed.

The polyurethane foams of this invention having reduced smoke generationare virtually any fire-retardant foam formulation formed by reacting anorganic polyisocyanate with an active hydrogen-containing material, andcontaining a'phosphorus fire retardant.

The active hydrogen'material may be virtually any activehydrogen-containing material employed as a urethane reactant, such as anorganic polyol. Preferably the activehydrogen-containing material is anorganic compound'or resin having an isocyanate equivalent between about70 and about 280. The presently preferred groups are-polyether polyolshaving a hydroxyl value between about 200 and about 800, such as thereaction product of a: polyhydroxylcompound containing 3 to 8 hydroxylgroups and an alkylene oxide containing 2 to 4 carbon atoms. Mostpreferably, the polyether polyol consists essentially of carbon,hydrogen andoxygen.

The reactive hydrogen-containing compounds which are conventionallyemployed in preparing polyurethane foams include as a chief classvarious long-chain aliphatic polyols, polyether polyol, polyesterpolyols and the like. Aliphatic polyols useful in this invention includethose diols which are separated by a carbon chain of 6 to or more carbonatoms; Since such diols are only difunctional,

they are ordinarily included only as minor amounts as a reactant in foamformulations designed to produce the novel rigid foams of thisinvention. For purposes of this invention, minor amounts of aliphaticdiols may be defined as amounts which do not detract from the rigidityof the cured foam nor detract from the excellent dimensional stabilityof the foam.

Aliphatic triols such as hexanetriol and polyether polyols prepared bythe oxyalkylation of said aliphatic triols, may be used in minor ormajor quantities in the foam formulation of this invention. It ispreferred, however, that additional reactive hydrogen components be morethan trifunctional and that the trifunctional polyols and polyetherpolyols be used in relatively minor quantities. The aliphatic triolswhich may be included as an additional reactive hydrogen componentinclude aliphatic triols having 6 or more carbon atoms. Typical triolsinclude the following: trimethylolethane, trimethylolpropane, glycerol,1,2,6-hexanetriol and the like. The trifunctional polyether polyolsuseful in the preparation of rigid polyurethane foams have a hydroxylnumber in excess of about 200 and preferably should have a hydroxylnumber in excess of about 300.

Tetrafunctional polyether polyols and polyether polyols of higherfunctionality are prepared by the reaction of an alkylene oxide, such asethylene oxide, propylene oxide or butylene oxide, with a polyol having4 or more available hydroxyl groups. Typical tetrafunctional and higherfunctional polyether polyol are prepared by the oxyalkylation of polyolssuch as the following: pentaerythritol, sucrose, 2,2,6,6-tetrakis(hydroxymethyl)cyclohexanol, glucose, sorbitol, mannitol, degradedstarches, degraded cellulose, diglycerol, a-methyl glucoside and thelike. When such polyether polyols are utilized in the novel rigidpolyurethane foams of this invention, they should have a hydroxyl numberin excess of about 200 and preferably in excess of about 250, with thebest results ordinarily being achieved from those polyether polyolshaving hydroxyl numbers in excess of about 300.

In addition to the aliphatic polyols and the polyether polyols,polyester resins containing hydroxyl groups may be utilized to prepareuseful rigid polyurethane foams. Suitable polyester resins may beprepared by reacting an excess of polyol with a polycarboxylic acid,especially dicarboxylic acids. Typical polyols include: ethylene glycol;propylene glycol; butylene glycol; glycerol; trimethylolpropane;trimethylolethane; 1,2,6-hexanetriol; pentaerythritol; diethyleneglycol; dipropylene glycol; and the like. Typical dicarboxylic acidsinclude: adipic acid, succinic acid, azaleic acid, phthalic acid,isophthalic acid, terephthalic acid, chlorendic acid, tetrabromophthalicacid and the like, and the corresponding anhydrides where suchanhydrides exist. Also, long chain dimer acids may be used to formuseful polyols by esterification with polyols, especially diols such asethylene glycol and the like. For the purposes of this invention, usefulpolyesters should have a minimum hydroxyl number of about 200, andpreferably above about 250, with best results being obtained from thosepolyesters having hydroxyl numbers in excess of about 300.

Another useful class of polyols which can be employed are thetrialkanolarnines which. by reaction with alkylene oxides, form adductsof suitable molecular weight, and the alkylene oxide adducts thereof.Illustrative of the lower molecular weight trialkanolarnines includetriethanolamine, triisopropanolamine and tributanolamine. The alkyleneoxide adducts which can be employed are preferably those wherein theoxyalkylene moieties thereof have from 2 to 4 carbon atoms.

Another useful class of polyols which can be employed are the alkyleneoxide adducts of monoand polyamines and also ammonia. These may betermed aminic polyols.

The monoand polyamines are preferably reacted with alkylene oxides whichhave 2 to 4 carbon atoms, for example, ethylene oxide; 1,2-epoxypropane,the epoxybutanes; and mixtures thereof. Monoand polyamines suitable forreaction with alkylene oxides include, among others, methylamine,ethylamine, isopropylamine, butylamine, benzylamine, aniline, thetoluidines, naphthylamines, ethylenediamine, diethylenetriamine,triethylenetetramine, 1,3-butanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,2-, 1,3-, 1,4- 1,5- and 1,6-hexanediamine,phenylenediamines, toluenediamine, naphthalenediamines and the like.Among the compounds of the above groups which are of particular interestare, among others, N,N,N,N' tetrakis(2 hydroxyethyl)ethylenediamine;N,N,N',N'- tetrakis(2-hydroxypropyl)ethylenediamine; N,N,N',N'pentakis,(2 hydroxypropyl)diethylenetriamine; phenyldiisopropanolamineand higher alkylene oxide adducts of aniline, and the like. Others whichdeserve particular mention are the alkylene oxide adducts of aniline orsubstituted aniline/formaldehyde condensation products.

Other active hydrogen-containing materials which may be present in thenovel urethane foams of this invention include phenol-formaldehydecondensation products, aminic compounds such as diethanolamine,triethanolamine and the like. Another material which may be present inthe foams of this invention is castor oil and its derivatives. Alsouseful are the oxyalkylation products of polyaminepolyamide compounds asobtained by the reaction of dicarboxylic acids with polyamines.

It is obvious that where the active hydrogen compound contains halogenssuch as chlorine or bromine or nitrogen, since these elements contributeto fire retardancy, a lesser amount of phosphorus compound may benecessary than where the active hydrogen-containing material consistsessentially of carbon, hydrogen and oxygen.

Organic polyisocyanates which are reacted with the active hydrogencompounds to form polyurethane foams include the following:

Toluene diisocyanate Chlorophenyl-2,4-diisocyanate Ethylene diisocyanate1,4-tetramethylene diisocyanate Para-phenylene diisocyanateHexamethylene diisocyanate and the like. While the above diisocyanatesmay be reacted with the active hydrogen-containing material to formfoams, it is preferred to form prepolymers of said diisocyanates whenthey are to be used in rigid foam formulations.

When it is desired to form polyurethane foams directly from an organicpolyisocyanate and the active hydrogencontaining materials without firstpreparing a prepolymer, it is preferred that poly-nuclearpolyisocyanates of the following type be included:

Diphenyl diisocyanate Triphenyl diisocyanate3,3-dimethyl-4,4'-biphenylene diisocyanate3,3'-dimethoxy-4,4'-biphenylene diisocyanate Polymethylene polyphenylisocyanate Diphenylmethane-4,4'-diisocyanate Triphenylmethanetriisocyanate 1,5 -naphthalene diisocyanate3,3-dimethyldiphenylmethane-4,4'-diisocyanate and the like. Of thepreferred polyisocyanates, it has been found that the best results havebeen obtained when the polymeric polyisocyanates having a functionalitygreater than 2.0 are utilized. Exemplary polymeric polyisocyanatesinclude the following:

Crude diphenylmethane 4,4-diisocyanate, commonly referred to as crudeMDI having a functionality of about 2.5 to 2.6. Furthermore, althoughsolid organic polyisocvanates can be utilized in the instant inventionby melting them prior to reaction with other foam-forming 4 ingredients,it is preferred that liquid organic polyisocyanates be utilized.

Another organic polyisocyanate particularly useful is crude tolylenediisocyanate, commonly referred to as crude TDI, containing aboutpercent TDI and about 15 percent polymeric isocyanate and having afunctionality of about2.l. m

Polymethylene polyphenyl isocyanate, referredto as PAPI, having anisocyanate functionality greater than about 2.4, has been found to beparticularly useful.

Polyurethane foams are prepared by'reacting approximately one equivalentof active hydrogen-containing resin with one equivalent ofan organicpolyisocyanate. It is frequently desirable to include a small amount ofsuitable urethane catalyst and there is also ordinarily included in foamformulations suitable emulsifiers and blowing agents.

The relative amount of organic isocyanate utilized in polyurethane foamformulations is susceptible to variation over a substantial range.Usually the isocyanatecomponent is employed in an amount which providesapproximately one reactive isocyanate group'for each reactive hydrogenof the other compound, which is conventionally a polyol, polyamine orsimilar reactive hydrogen-containing material. However, some of theorganic polyisocyanates tend to evaporate and it may be desirable tocompensate for this loss. A range of about one-half equivalent to abouttwo equivalents of organic polyisocyanate per equivalent of polyolcomponent in the final material is ordinarily used, but smaller orlarger amounts can be utilized with good results.

To promote the polyurethane linkage reactions in the cfinal curing ofthe polyurethane resins, catalysts are usually required. These includetertiary amines of hydroxyl amines, organic salts of tin, and the like.The following constitutes a partial list of such catalysts:

Tetramethylethylenediamine (anhydrous) (TMEDA) Tetramethyl guanidine(TMG) i Tetramethyl-1,3-butanediamine (TMBDA) Triethylenediamine of theformula:

Dimethylethanolamine, (D'MEA) Tin esters, such as Stannous oleateStannous octoate Dibutyl tin diluarate -Dibutyl tin diacetate To imparta foamed orcellular structure to theblended,

polyol-polyisocyanate mixture, a suitable gassing agent-or system ofgassing agents mustbe added or produced in situ. The liquid butrelatively volatile halocarbons, such as the following perhalocarbonscontaining'1,.2 or even up to 4 carbon atoms, areespeciallydesirable forthe purpose. These include the following.

CCI3F 0 01 12, "'CCIF3 The halocarbons having onetand two carbon atoms.are

preferred, and of these, trichloromonofluoromethane anddichlorodifluoromethane are particularly :useful in-,com-:

mercial preparations. These are added asliquids in'quantities of about10 percent or less to about ZO percent-or more, by weight of the totalresin to the blended polyolpolyisocyanate mixtures, or to one or morecomponents thereof, and are substantially volatilized in the liquidmixture to effect cellulation. Subsequently, the mixture cures to ahardened, cellular state.

especially if denser foams are desired. Many hundreds of these areavailable as commercial products. Some of these are listed in thepublication Detergents and Emulsifiers Up to Date, published by John W.McCutcheon, Inc., 475 Fifth Avenue, New York, N..Y.

Examples of surfactants which may be used include the so-calledPluronics, which have been described as being condensates of ethyleneoxide with a hydrophobic base formed by condensing propylene oxide withpropylene glycol. These are of a molecular weight in a range of about2000 to about 8000 and are ascribed the structure:

Another class of surfactants comprises the so-called Tetronics, whichare formed by the addition of propylene oxide to ethylene diamiue,followed by the addition of ethylene oxide. These compounds have beenascribed the structure:

H 2 4 t a 6 s Another valuable class of surfactants comprises thesocalled Tweens, which are described as the monoesters of higher fattyacids, represented by lauric acid, stearic acid and oleic acid, andpolyoxyethylene sorbitan.

Another of the more satisfactory surfactants which has been found veryeffectively to maintain the cell structure in the foaming and curing ofpolyurethane resins comprises soluble, liquid derivatives of thesilicones. One such product is of the aproximate structure:

(QC-3H6) s 2 4 e o (R 510) r tc n o) ZR" in which R' and R aremonovalent hydrocarbon radicals, while R is a divalent hydrocarbonradical; p, q and r are integers equal to at least 1 and may beconsiderably higher, e.g., 2, 3, 4, 5, 6 or a higher number up to about20; n is a whole number from about 2 to about 4; and z is an integerequal to at least 5 and may be higher, e.g., 6, 7, 8, 9, or even higher,up to about 25. One such material is sold as Dow-Corning 199. Stillanother highly useful silicon base surfactant comprises the so-calledsilicon L-52, represented by the following formula:

SiO C2H4O C3H O (141-19 ployed in amounts within a range of about 0.1 toabout 3 percent by weight based upon the mixture of polyol component andthe organic polyisocy-anate component. In relatively dense foams, forexample, those weighing about 5 or 6 pounds and upward per cubic foot,the surfactants may be omitted entirely.

The foams employed in the composition of this in vention are foams whichare self-extinguishing under the standards set forth in ASTM D196259T.Generallly, the minimum amount of phosphorus is about 0.5 to about 2.0percent depending on the formulation.

The phosphorus which contributes to fire-retardancy may be in the formof a reactive or a non-reactive phosphorus-containing compound. Thereactive phosphorus containing compound may either be a phosphoruscompound containing active hydrogen groups such as a polyol or may be aphosphorus-containing isocyanate. The nature of the phosphrous compoundis, in fact, the nature of the active hydrogen compound or theisocyanate generally. It is in no manner critical and all such materialsconventionally employed in the art may be employed in the foams of theinvention. A great many phosphoruscontaining materials which may beincorporated in the polyurethane foams to achieve fire-retardancy areknown in the art. These materials can be found, for example, in the US.Patent Classification Class 260, subclass 2.5. To enumerate at lengthall the possible materials is deemed unnecessary since one need merelyrefer to the art to determine what materials are available. Thephosphorus-containing polyols include those derived from phosphorus,phosphonic, phosphoric, and pyrophosphoric acids. The polyols of theseacids may be prepared in a number of ways such as reacting the acidswith alkylene oxides, or halogen-substituted alkylene oxides or byesterification of the acids or transesterification of acid esters withpolyalkylene glycols and polyoxyalkylene glycols. One particularlyuseful class of polyols is the product of the oxyalkylation of an acidester formed from oxyaci-d of phosphorus and a monohydric alcoholdescribed in US. Pat. No. 3,407,150. Other polyols which may be employedinclude diethyl N,N diethanolaminomethyl phosphonate (Fyrol #6),bis(hydroxypolypropoxypropyl) N,N-diethanolaminomethyl phosphonate,tris(hydroxypropyl) phosphate, tris[octakis(2-hydroxypropyl)sucrose1phosphite, tris dipropylene glycol phosphite,tris[tetrakis(2 hydroxypropyna methyl glycoside]phosphite.

Non-reactive phosphorus fire-retardant agents includetris(chloroethyl)phosphate, tris(chloropropyl)phosphate, tris(2,3dichloropropyl)phosphate, tris(2,3 dibromopropyl)phosphate,bis(beta-chloroethyDvinyl phosphate.

Phosphorus-containing polyisocyanates include ethylphosphonicdiisocyanate, C H P(O)(NCO) phenylphonous diisocyanate, C H P-(NCO) Thefollowing examples set forth a presently preferred embodiment. All partsand percentages in the examples as well as throughout the specificationare by weight unless otherwise indicated.

The polyol employed in this example was a sucrose polyethe r polyol asdescribed in US. Pat. Nos. 3,085,- 085; 3,153,002 and 3,222,357 andelsewhere comprising one mole of sucrose, 0.4 mole diethylenetriamine,14.5 moles of pyropylene oxide and 4 moles of ethylene oxide with an OHof 470.

The isocyanate employed was Mondur-MR, a p,p-diphenylmethanediisocyanate with a functionality of 2.5 to 2.6 and an NCO equivalent of133.

The fire-retardant additive wasdiethyl-N,N'-diethanolaminomethylphosphonate.

The following masterbatch was prepared:

EXAMPLE I Parts by weight Polyol (above) 1731. 0 Fire retardant (above)912.0 Silicone surfactant 30.0

7 EXAMPLE IContinued Parts by weight Dibutyl tin diacetate 6.0Trichloromonofiuoromethane 888.0

All the following foams were made by foaming 118.9 parts of themastenbatch with a blend of 100 parts isocyanate with levels of acid at10 parts, 30 parts and 50 parts. The masterbatch was at 65 F. and theacid isocyanate blend at 77 F. All foamable mixtures were mixed for 10seconds.

cloth. The samples were covered with an inverted 3 /4 inch diameterfritted glass funnel. The funnel walls were 3 /2 inch deep and thefunnel had a inch diameter throat. The throat of the funnel wasconnected to a vacuum source. The funnel contains a piece of glass fiberfilter placed over the fritted glass.

With vacuum on, the foam samples were burnedusing a 3 /2 inch Bunsenburner with the top of the burner 1% inch below the wire cloth and aflame 3 inches high. The

10 flame was held on the sample for the time indicated. The

TABLE I 7 Cream Set Density,

Foam Level, time, time, 1b./c11. designation Additive parts secondsseconds Foam description it.

A Control 19 45 Good foam, fine cells .4 2.3 B Chlorendic acid- 10 19 542. 2 O do 30 10 55 Tough, good 10am; some undissolved material,especially at 50 parts.-- 2.6 D -do 50 19 87 2. 55 E Oxalic acid 10 42111 I i 1.27 F do 15 51 142 Very low density foams; dark spots ininterior of foam 1. 43 G (lo 30 27 154 1. 37 H Malele anhy- 10 31 101 12.1 I 30 34 152 Red ioamheat cracks and large voids in team 201 .T d O36 202 y I 2.1 L Citric acid 30 19 43 Little undissolved material 2. 82M Benzoic acid 30 86 111 Some undissolved material 2.89 N Malic acid 47s a 2.3 O do 30 19 49 Tough foamsome undissolved material 2. 74 P do 5065 2. 8 R Malic acid 10 12 32 2. 1 S do 14 42 Brown spots inside, largeholes and some heat cracks 2. 1 T d0 9 57 1. 8

Smoke density studies [Reference: Cass, R. A., Journal 30 foam samplewas allowed to flame out. The sample was of Cellular Plastics 3, 1, 41(1967)] were conducted on the above foams in the following manner:

Cylindrical foam samples, one inch long, 0.765 inch in diameter, wereplaced on a inch mesh hardware removed after flameout and placed in a.sealed vial. The

glass filter was removed and placed in a petri dish. All" samples andfilters were weighed before and after the test.

The result of the sample burnings were as follows:

TABLE II Percent weight Percent smoke Level, Foam Additive partsRemaining Loss Collected Average 16. 9 83.1 14. 7 A Control 17. 45 82.11. 7 12. 5

17.6 82.4 V 11.1, p 10 19.2 89. 8 13. 1 13 Chlorendic acid 10 19. 1 80.9 11. 3 11. 3-

10 19. 2 80. 8 11. 1 30 26. 0 74. 0 a 9. 55 C do 30 24. 2 75. 8 8. 488.89, 30 22. 8 77. 2 8. 64 ,7 50 27.4 72. 6 6. 44 D do 50 32. 9 67. 2 3.88 5. 66

50 27. 9 22. 1 6. 68 10 17. 0 83. 0 17. 4 E oxalic acid 10 16. 3 83. 715. 2 14. 6

10 17. 1 82. 9 11. 3 15 15. 0 85. 0 12. 2 F d0 15 15. 9 84. 1 19. 5 10.8 15 16. 4 83. 6 9. 8 3O 16. 25 83. 11. 15 G d0 30 16. 9 83. 10 10. 13.3

30 17. 0 83. 00 17. 95 7 1o 22. 5 I 77.5 7.88 v H Malelc anhydride 1023. 4 76. 6 7. 22 6. 9 19 25. 7 74. 3 5. 53 30 26. 8 73. 2 7. 27 I do 3027. 4 72. 6' 6. 98 6. 4

50 I 32. 8 67. 2 4-. 58 30 18. 9 81. 1 8. 50 L Citric acid 30 18. 4 81.6 9. 6O 8. 9

' 30 18. 2 81. 8 9. 94 M Benzoic acid 30 17. 2 81. 8 9. 06 9. 7

30 16. 2 83. 8 10. 15 10 24. 5 75. 5 6. N Malic acid 10 19. 5 80. 5 12.25 10. 2

10 18. 7 81.3 11.60 30 22. 5 77. 5 7. 75 O --do 30 23. 2 76. 8 8.07 7. 7

30 22. 9 77. 1 7. 18 50 34. 2 e5. 8 4. 77 P do 50 37. 6 72. 4 7. 43 *5.5

50 30. 5 69. 5 4. 32 10 19. 8 80. 2 16. 0 R Malelc acid 10 20. 8 79. 213. 0 13. 7

10 21. 7 78. 3 12. 6 30 25. 9 74. 1 8. 31 S do 30 27. 0. 73. 0 5. 72 7.6

Other isocyanates, reactive hydrogen materials and phosphorus compoundssuch as those described hereinabove can be substituted for those of theexamples. Likewise, the adjuvant-s such as cellulating agent,emulsifier, catalyst, etc., may be chosen from those known in the art.

According to the provisions of the patent statutes, there are describedabove the invention and what are now considered its best embodiments;however, within the scope of the appended claims, it is understood thatthe invention can be practiced otherwise than as specifically described.

What is claimed is:

1. A polyurethane foam formed by foaming a mixture comprising:

(A) an organic polyisocyanate;

(B) anorganic polyol;

(C) a phosphorus-containing fire-retardant organic material in an amountsufficient to render the final foam self-extinguishing;

'(D) a smoke-inhibiting amount of the organic compound chlorendic acid;and

(E) acellulating agent.

2. A foam as in claim 1 wherein (B) has an isocyanate equivalent ofabout 70 to about 280; (C) is a material reactive in the foamablemixture; and (D) is present in an amount of about percent to about 40percent by weight of the total composition.

3. A foam as in claim 1 wherein (B) comprises a polyether polyol whichis the reaction product of a polyhydroxyl compound containing 3 to 8hydroxyl groups and an alkylene oxide containing 2 to 4 carbon atoms permolecule.

4. A foam as in claim 3 wherein (B) has a hydroxyl value of about 200 toabout 800; (C) is a material reactive in the foamable mixture; and (D)is present in an amount of about 5 percent to about 40 percent of thetotal composition.

5. A foam as in claim 4 wherein the polyol comprises a sucrose polyetherpolyol.

6. A polyurethane foam as in claim 1 formed from a mixture comprising:

(A) an organic polyisocyanate;

(B) an organic polyol having an isocyanate equivalent between about 70and about 280;

(C) a phosphorus-containing fire-retardant organic material in an amountsufficient to render the final foam self-extinguishing;

(D) a smoke-inhibiting amount of the organic compound chlorendic acid;

(E) a cellulating agent; and

(F) an emulsifier for the mixture.

7. A foam as in claim 6 wherein (B) comprises a polyether polyol whichis the reaction product of a polyhydroxyl compound containing 3 to 8hydroxyl groups and an alkylene oxide containing 2 to 4 carbon atoms permolecule.

8. A foam as in claim 6 wherein (B) has a hydroxyl value above about250.

9. A foam as in claim 8 wherein (C) is a material reactive in thefoamable mixture.

10. A foam as in claim 8 wherein the polyol comprises a sucrosepolyether polyol.

11. A polyurethane foam formed by foaming a mix ture comprising:

(A) an organic polyisocyanate;

(B) an organic polyol;

(C) a phosphorus-containing fire-retardant organic material in an amountsufficient to render the final foam self-extinguishing;

(D) a smoke-inhibiting amount of the organic compound chlorendic acid;and

(E) a halocarbon blowing agent.

12. A foam as in claim 11 wherein (B) has an isocyanate equivalent ofabout to about 280; (C) is a material reactive in the foamable mixtureand (D) is present in an amount of about 5 percent to about 40 percentby weight of the total composition.

13. A foam as in claim 11 wherein (B) comprises a polyether polyol whichis the reaction product of a polyhydroxyl compound containing 3 to 8hydroxyl groups and an alkylene oxide containing 2 to 4 carbon atoms permolecule.

14. A foam as in claim 13 wherein (B) has a hydroxyl value of about 200to about 800; (C) is a material reactive in the foamable mixture; and(D) is present in an amount of about 5 percent to about 40 percent ofthe total composition.

15. A foam as in claim 14 wherein the polyol comprises a sucrosepolyether polyol.

16. A polyurethane foam as in claim 11 formed from a mixture comprising:

(A) an organic polyisocyanate;

(B) an organic polyol having an isocyanate equivalent between about 70and about 280;

(C) a phosphorus-containing fire-retardant organic material in an amountsufficient to render the final foam self-extinguishing;

(D) a smoke-inhibiting amount of the organic compound chlorendc acid;

(E) a hydrocarbon blowng agent; and

(F) an emulsifier for the mixture.

17. A foam as in claim 16 wherein (B) comprises a polyether polyol wihchis the reaction product of a polyhydroxyl compound containing 3 to 8hydroxyl groups and an alkylene oxide containing 2 to 4 carbon atoms permolecule.

18. A foam as in claim 16 wherein (B) has a hydroxyl value above about250.

19. A foam as in claim 18 wherein (C) is a material reactive in thefoamable mixture.

20. A foam as in claim 18 wherein the polyol comprises a sucrosepolyether polyol.

References Cited UNITED STATES PATENTS 5/1966 Schoepfle 260-25 Schoeplle2602.5

US. Cl. X. R.

2602.5 AM, 2.5 AS, 2.5 AR

